From: Martin Kepplinger <martin.kepplinger@puri.sm> To: Alan Stern <stern@rowland.harvard.edu> Cc: Bart Van Assche <bvanassche@acm.org>, Can Guo <cang@codeaurora.org>, linux-scsi@vger.kernel.org, linux-block@vger.kernel.org, kernel@puri.sm Subject: Re: [PATCH] block: Fix bug in runtime-resume handling Date: Thu, 27 Aug 2020 19:42:43 +0200 [thread overview] Message-ID: <4c636f2d-af7f-bbde-a864-dbeb67c590ec@puri.sm> (raw) In-Reply-To: <5152a510-bebf-bf33-f6b3-4549e50386ab@puri.sm> On 26.08.20 09:48, Martin Kepplinger wrote: > On 24.08.20 22:13, Alan Stern wrote: >> On Mon, Aug 24, 2020 at 10:48:32AM -0700, Bart Van Assche wrote: >>> On 2020-08-23 07:57, Alan Stern wrote: >>>> The problem is fixed by checking that the queue's runtime-PM status >>>> isn't RPM_SUSPENDED before allowing a request to be issued, [ ... ] >>> >>> Reviewed-by: Bart Van Assche <bvanassche@acm.org> >>> >>> Can, can you help with testing this patch? >>> >>> Thanks, >>> >>> Bart. >> >> Martin: >> >> (I forgot to ask this question several weeks ago, while you were running >> your tests. Better ask it now before I forget again...) >> >> I suspect the old runtime-PM code in the block layer would have worked >> okay in your SD cardreader test if the BLK_MQ_REQ_PREEMPT flag had not >> been set. Do you know why the flag was set, or what line of code caused >> it to be set? > > Correct. if not set, I could handle all I need in the scsi error path. this thread becomes a bit confusing. I thought about REQ_FAILFAST_DEV but you're talking about something different. the only place I see BLK_MQ_REQ_PREEMPT getting passed on is in __scsi_execute() which is the case when mounting/unmounting. At least that about the only place I can find. I remember *only* your block pm fix would let me mount/unmount, but not use files yet (REQ_FAILFAST_DEV and so on). When I revert your fix and remove BLK_MQ_REQ_PREEMPT from being passed on to blk_get_request() in __scsi_execute(), that line gets executed exactly once during startup and I'm missing the /dev/sda device from the cardreader then. Is this what you're asking? > >> >> As I recall, the request that failed was a read-ahead. It's not clear >> to me why such a request would need to have BLK_MQ_REQ_PREEMPT set. >> Although there may be other reasons for having that flag, at this point >> we're concerned with requests that are part of the runtime-resume >> procedure. A read-ahead does not fall into that category. >> >> Do you think you can find the answer? Perhaps we should add a separate >> BLK_MQ_REQ_PM flag.
next prev parent reply other threads:[~2020-08-27 17:43 UTC|newest] Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-06-23 11:10 [PATCH] scsi: sd: add runtime pm to open / release Martin Kepplinger 2020-06-24 13:33 ` Bart Van Assche 2020-06-25 8:16 ` Martin Kepplinger 2020-06-25 14:52 ` Alan Stern 2020-06-26 3:53 ` Bart Van Assche 2020-06-26 15:07 ` Bart Van Assche 2020-06-26 15:44 ` Alan Stern 2020-06-28 2:37 ` Bart Van Assche 2020-06-28 13:10 ` Alan Stern 2020-06-29 9:42 ` Martin Kepplinger 2020-06-29 16:15 ` Alan Stern 2020-06-29 16:56 ` Bart Van Assche 2020-06-29 17:40 ` Alan Stern 2020-06-30 3:33 ` Martin Kepplinger 2020-06-30 13:38 ` Alan Stern 2020-06-30 15:59 ` Bart Van Assche 2020-06-30 18:02 ` Alan Stern 2020-06-30 19:23 ` Bart Van Assche 2020-06-30 19:38 ` Alan Stern 2020-06-30 23:31 ` Bart Van Assche 2020-07-01 0:49 ` Alan Stern 2020-07-06 16:41 ` Alan Stern 2020-07-28 7:02 ` Martin Kepplinger 2020-07-28 20:02 ` Alan Stern 2020-07-29 14:12 ` Martin Kepplinger 2020-07-29 14:32 ` Alan Stern 2020-07-29 14:44 ` Martin K. Petersen 2020-07-29 14:56 ` Alan Stern 2020-07-29 14:46 ` James Bottomley 2020-07-29 14:53 ` James Bottomley 2020-07-29 15:40 ` Martin Kepplinger 2020-07-29 15:44 ` James Bottomley 2020-07-29 16:43 ` Martin Kepplinger 2020-07-29 18:25 ` Alan Stern 2020-07-29 18:29 ` James Bottomley 2020-07-30 8:52 ` Martin Kepplinger 2020-07-30 8:54 ` Martin Kepplinger 2020-07-30 15:10 ` Alan Stern 2020-08-04 9:39 ` Martin Kepplinger 2020-08-07 9:51 ` Martin Kepplinger 2020-08-07 14:30 ` Alan Stern 2020-08-08 6:59 ` Martin Kepplinger 2020-08-08 15:05 ` Alan Stern 2020-08-09 9:20 ` Martin Kepplinger 2020-08-09 15:26 ` Alan Stern 2020-08-10 12:03 ` Martin Kepplinger 2020-08-10 14:13 ` Alan Stern 2020-08-11 7:55 ` Martin Kepplinger 2020-08-11 13:48 ` Alan Stern 2020-08-23 14:57 ` [PATCH] block: Fix bug in runtime-resume handling Alan Stern 2020-08-24 17:48 ` Bart Van Assche 2020-08-24 20:13 ` Alan Stern 2020-08-26 7:48 ` Martin Kepplinger 2020-08-27 17:42 ` Martin Kepplinger [this message] 2020-08-27 20:29 ` Alan Stern 2020-08-29 7:24 ` Martin Kepplinger 2020-08-29 15:26 ` Alan Stern 2020-08-29 16:33 ` Martin Kepplinger 2020-08-29 18:56 ` Alan Stern 2020-08-30 0:38 ` Bart Van Assche 2020-08-30 1:06 ` Alan Stern 2020-07-29 15:40 ` [PATCH] scsi: sd: add runtime pm to open / release Alan Stern 2020-07-29 15:49 ` James Bottomley 2020-07-29 16:17 ` Alan Stern 2020-07-29 15:52 ` Martin Kepplinger 2020-07-29 18:10 ` Douglas Gilbert 2020-07-30 8:05 ` Martin Kepplinger 2020-07-30 15:14 ` Alan Stern
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